/*
 *  include/asm-ckcore/checksum.h
 *
 *  Copyright (C) 2009  Hangzhou C-SKY Microsystems
 */

#ifndef _CK640_CHECKSUM_H
#define _CK640_CHECKSUM_H

#include <linux/in6.h>
/*
 * computes the checksum of a memory block at buff, length len,
 * and adds in "sum" (32-bit)
 *
 * returns a 32-bit number suitable for feeding into itself
 * or csum_tcpudp_magic
 *
 * this function must be called with even lengths, except
 * for the last fragment, which may be odd
 *
 * it's best to have buff aligned on a 32-bit boundary
 */
 __wsum csum_partial(const void * buff, int len, __wsum sum);

/*
 * the same as csum_partial, but copies from src while it
 * checksums
 *
 * here even more important to align src and dst on a 32-bit (or even
 * better 64-bit) boundary
 */

__wsum csum_partial_copy(const void *src, void *dst, int len, __wsum sum);


/*
 * the same as csum_partial_copy, but copies from user space.
 *
 * here even more important to align src and dst on a 32-bit (or even
 * better 64-bit) boundary
 */

extern __wsum csum_partial_copy_from_user(const void __user *src, void *dst,
						int len, __wsum sum, int *csum_err);

#define csum_partial_copy_nocheck(src, dst, len, sum)	\
	csum_partial_copy((src), (dst), (len), (sum))

extern __sum16 ip_fast_csum(const void *iph, unsigned int ihl);


/*
 *	Fold a partial checksum
 */

static inline __sum16 csum_fold(__wsum sum)
{
	unsigned int temp = 0;

	temp = (sum & 0xffff);
	temp  += (sum >> 16);
	if (temp < (sum >> 16))	//We must take account of the carry bit.
	{
		sum = temp + 1;
	}
	else
	{
		sum = temp;
	}

	temp = (sum & 0xffff); 
        temp  += (sum >> 16);
        if (temp < (sum >> 16))
        {
                sum = temp + 1;
        }
	else
	{
		sum = temp;
	}
	return ~sum;
}


/*
 * computes the checksum of the TCP/UDP pseudo-header
 * returns a 16-bit checksum, already complemented
 */

static inline __wsum
csum_tcpudp_nofold(__be32 saddr, __be32 daddr, unsigned short len,
		  unsigned short proto, __wsum sum)
{
	sum += saddr;
	if (sum < saddr)	//We must take account of the carry bit.
	{
		sum += 1;
	}
	sum  += daddr;
	if (sum < daddr)
	{
		sum += 1;
	}
	sum += len;
	if (sum < len)
	{
		sum += 1;
	}
	sum += proto;
	if (sum < proto)
	{
		sum = sum + 1;
	}
	return sum;
}

static inline __sum16
csum_tcpudp_magic(__be32 saddr, __be32 daddr, unsigned short len,
		  unsigned short proto, __wsum sum)
{
	return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
}

/*
 * this routine is used for miscellaneous IP-like checksums, mainly
 * in icmp.c
 */

extern __sum16 ip_compute_csum(const void * buff, int len);

#define _HAVE_ARCH_IPV6_CSUM
static __inline__ __sum16
csum_ipv6_magic(const struct in6_addr *saddr, const struct in6_addr *daddr,
		__u32 len, unsigned short proto, __wsum sum) 
{
//	register unsigned long tmp;
        sum += saddr->in6_u.u6_addr32[0];
        sum += saddr->in6_u.u6_addr32[1];
        sum += saddr->in6_u.u6_addr32[2];
        sum += saddr->in6_u.u6_addr32[3];
        sum += daddr->in6_u.u6_addr32[0];
        sum += daddr->in6_u.u6_addr32[1];
        sum += daddr->in6_u.u6_addr32[2];
        sum += daddr->in6_u.u6_addr32[3];
        sum += (len + proto);
	return csum_fold(sum);
}

#endif /* _CK640_CHECKSUM_H */
